Spin-parity JP Research Articles

Triply charm and bottom tetraquarks in a constituent quark model

Singly, doubly, and fully charmed tetraquark candidates, e.g., Tcs¯(2900), Tcc+(3875), and X(6900) have been recently reported by the LHCb collaboration. Therefore, it is timely to implement a theoretical investigation on triply heavy tetraquark systems; herein, the S-wave triply charm and bottom tetraquarks, Q¯Qq¯Q (q=u,d,s;Q=c,b), with spin-parity JP=0+, 1+, and 2+, isospin I=0 and 12, are systematically studied in a constituent quark model. Besides, all tetraquark configurations, i.e., meson-meson, diquark-antidiquark, and K-type arrangements, along with any allowed color structure, are comprehensively considered. The Gaussian expansion method (GEM), in combination with the complex-scaling method (CSM), which is quite ingenious in dealing with either bound or resonances, is the approach adopted in solving the complex scaled Schrödinger equation. This theoretical framework has already been applied in various tetra- and pentaquark systems. In a fully coupled-channel calculation within the GEM+CSM, narrow resonances are found in each I(JP) channel of the charm and bottom sector. In particular, triply charm and bottom tetraquark resonances are obtained in 5.6–5.9 GeV and 15.3–15.7 GeV, respectively. We provide also some insights of the compositeness of these exotic states, such as the inner quark distance, magnetic moment and dominant wave function component. All this may help to distinguish them in future high energy nuclear and particle experiments. Published by the American Physical Society 2024

Studying the Ξ(2030) as a predominantly K¯*Σ molecular state

Since its discovery in 1977, the spin parity of Ξ(2030) has not been fully determined experimentally. The latest Particle Data Group listing suggests it may be a baryon with J=5/2. Therefore, studying the mass spectrum and decay properties of Ξ(2030) has become a current hot topic to definitively establish its spin parity. As the three-quark model fails to explain Ξ(2030), we previously proposed it may be a molecule primarily composed of K¯*Σ with JP=5/2+, based on its mass spectrum study. To verify its molecular state interpretation, this work proposes studying the strong decays of Ξ(2030) assuming it is a P-wave JP=5/2+ meson-baryon molecule predominantly composed of K¯*Σ. We calculated all experimentally measured two-body and three-body final state decay widths of Ξ(2030), including Ξ(2030)→K¯Λ,K¯Σ,πΞ,πΞ*, and Ξ(2030)→ππΞ,πK¯Σ,πK¯Λ. The results indicate that both the total decay width and partial decay widths agree well with experimental values within the error margins. This supports that Ξ(2030) is a molecule with spin-parity JP=5/2+, predominantly composed of K¯*Σ. Compared to the experimental central values, our results are slightly smaller, which suggests that Ξ(2030) may contain additional components besides meson-baryon molecular components, such as three-quark structures. Published by the American Physical Society 2024

Parameters of the tensor tetraquark [formula omitted]

The mass and width of the tensor tetraquark T=bbc‾c‾ with spin-parity JP=2+ are calculated in the context of the QCD sum rule method. The tetraquark T is modeled as a diquark-antidiquark state built of components bTCγμb and c‾γνCc‾T with C being the charge conjugation matrix. The mass m=(12.795±0.095)GeV of the exotic tensor meson T is found by means of the two-point sum rule approach. Its full width Γ is evaluated by considering processes T→Bc−Bc−, Bc−Bc⁎−, and Bc⁎−Bc⁎−. Partial widths of these decays are computed by means of the three-point sum rule approach which is used to determine the strong couplings at relevant tetraquark-meson-meson vertices. Predictions obtained for the width ΓT=55.5−9.9+10.6MeV, as well as the mass of the tetraquark T can be useful in investigations of fully heavy four-quark mesons.

Exploring the magnetic dipole moments of {T}_{QQoverline{q}overline{s}} and {T}_{QQoverline{s}overline{s}} states in the framework of QCD light-cone sum rules

Motivated by the recent observation of the tetraquark {T}_{cc}^{+} , we investigate the magnetic dipole moments of the possible single and double strange partners, {T}_{QQoverline{q}overline{s}} and {T}_{QQoverline{s}overline{s}} , with the spin-parity JP = 1+ by means of the QCD light-cone sum rules. To this end, we model these states as diquark-antidiquark states with different organizations and interpolating currents. The results of magnetic dipole moments obtained using different diquark-antidiquark structures differ from each other, considerably. The magnetic dipole moment is the leading-order response of a bound system to a soft external magnetic field. Therefore, it provides an excellent platform for investigation of the inner structures of hadrons governed by the quark-gluon dynamics of QCD.

Doubly heavy tetraquark resonant states

Spectrum of the doubly heavy tetraquarks, bbq¯q¯, is studied in a constituent quark model. Four-body problem is solved in a variational method where the real scaling technique is used to identify resonant states above the fall-apart decay thresholds. In addition to the two bound states that were reported in the previous study we have found several narrow resonant states above the BB⁎ and B⁎B⁎ thresholds. Their structures are studied and are interpreted by the quark dynamics. A narrow resonance with spin-parity JP=1+ is found to be a mixed state of a compact tetraquark and a B⁎B⁎ scattering state. This is driven by a strong color Coulombic attraction between the bb quarks. Negative-parity excited resonances with JP=0−, 1− and 2− form a triplet under the heavy-quark spin symmetry. It turns out that they share a similar structure to the λ-mode of a singly heavy baryon as a result of the strongly attractive correlation for the doubly heavy diquark.

Strong decays of the Pcs(4459) as a $$\Xi_{c}\bar{D}^{\ast}$$ molecule

In this work, we study the strong decay of the newly observed Pcs(4459), assuming that it is a pure \(\Xi_{c}\bar{D}^{\ast}\) molecular state. Considering two possible spin-parity assignments JP = 1/2− and JP = 3/2−, the partial decay widths of the \(\Xi_{c}\bar{D}^{\ast}\) molecular state into J/ψΛ, D −s Λ +c , and \(\bar{D}\Xi_{c}^{(\prime)}\) final states through hadronic loops are evaluated with the help of the effective Lagrangians. In comparison with the LHCb data, the S-wave \(\bar{D}^{\ast}\Xi_{c}\) molecular with JP = 1/2− assignment for Pcs(4459) is supported by our study, while the Pcs(4459) in spin-parity JP = 3/2− case may be explained as an S-wave coupled bound state with lager \(\Xi_{c}\bar{D}^{\ast}\) component. In addition, the calculated partial decay widths with JP = 1/2− \(\Xi_{c}\bar{D}^{\ast}\) molecular state picture indicate that allowed decay mode, \(\bar{D}^{\ast}\Xi_{c}^{\prime}\), may have the biggest branching ratio. The experimental measurements for this strong decay process could be a crucial test for the molecule interpretation of the Pcs(4459).

Analysis of the fully-heavy pentaquark states via the QCD sum rules

In the article, we investigate the diquark-diquark-antiquark type fully-heavy pentaquark states with the spin-parity JP=12− via the QCD sum rules for the first time, and obtain the masses Mccccc¯=7.93±0.15 GeV and Mbbbbb¯=23.91±0.15 GeV. We can search for the fully-heavy pentaquark states in the J/ψΩccc and ϒΩbbb invariant mass spectrum in the future.

Spin-parity assignments of excited -baryons in the Quark-Diquark Model

Recently the LHCb Collaboration have found four baryonic states called Ω b (6316), Ω b (6330), Ω b (6340), and Ω b (6350) in the invariant mass spectrum. Possible spin-parity assignments of these resonances in the Quark-Diquark Model as P-wave baryons are discussed. Parameters of the effective Hamiltonian are determined from the observed spectrum of -baryons and compared with the ones extracted from the mass spectrum of -baryons. Alternative interpretation, in which the three lowest-mass states have the spin-parities JP = 3/2−, 3/2−, 5/2−, predicts an -baryon with the mass M ≃ 6304 MeV which is not yet seen experimentally.

Radiative decays of heavy quarkonia into two vector mesons. Spin properties of amplitudes and angular distributions of linearly polarized photons

Angular distributions of photons with definite linear polarizations relative to the plane spanned by the momentum of initial electron and the total momentum of the V1V1 pair in the reaction e+e− → V → γ X (JP) → γV1V1 (V = J/ψ,ψ′,…, Υ(1S), Υ,… and V1 = ρ,ω,ϕ,…) are calculated. It is shown that the sign of asymmetry of the distributions of photons polarized in the above plane and orthogonal to it correlates with the signature P(−1)J of the X resonance with given spin-parity JP = 0±, 1±, 2± so it may help to establish this quantum number in a way which does not depend on the specific model of the X(JP) → V1V1 amplitude.

Search for the Σ⁎ state in [formula omitted] decay by triangle singularity

A Σ⁎ resonance with spin-parity JP=1/2− and mass in the vicinity of the K¯N threshold has been predicted in the unitary chiral approach and inferred from the analysis of CLAS data on the γp→K+π0Σ0 reaction. In this work, based on the dominant Cabibbo favored weak decay mechanism, we perform a study of Λc+→π+π0Σ⁎ with the possible Σ⁎ state decaying into π−Σ+ through a triangle diagram. This process is initiated by Λc+→π+K¯⁎N, then the K¯⁎ decays into K¯π and K¯N produce the Σ⁎ through a triangle loop containing K¯⁎NK¯ which develops a triangle singularity. We show that the π−Σ+ state is generated from final state interaction of K¯N in S-wave and isospin I=1, and the Λc+→π+π0π−Σ+ decay can be used to study the possible Σ⁎ state around the K¯N threshold. The proposed decay mechanism can provide valuable information on the nature of the Σ⁎ resonance and can in principle be tested by facilities such as LHCb, BelleII and BESIII.

First measurement of coherent ϕ -meson photoproduction from He4 near threshold

The differential cross sections and decay angular distributions for coherent ϕ-meson photoproduction from helium-4 are measured for the first time at forward angles with linearly polarized photons in the energy range Eγ=1.685–2.385GeV. Thanks to the target with spin-parity JP=0+, unnatural-parity exchanges are absent, and thus natural-parity exchanges can be investigated clearly. The decay asymmetry with respect to photon polarization is shown to be very close to the maximal value. This ensures the strong dominance (>94%) of natural-parity exchanges in this reaction. To evaluate the contribution from natural-parity exchanges to the forward cross section (θ=0∘) for the γp→ϕp reaction near threshold, the energy dependence of the forward cross section (θ=0∘) for the γHe4→ϕHe4 reaction is analyzed. The comparison to γp→ϕp data suggests that enhancement of the forward cross section arising from natural-parity exchanges and/or destructive interference between natural-parity and unnatural-parity exchanges is needed in the γp→ϕp reaction near threshold.Received 3 November 2017Revised 21 January 2018DOI:https://doi.org/10.1103/PhysRevC.97.035208©2018 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasParticle interactionsParticle productionPhotonuclear reactionsParticles & FieldsNuclear Physics

The Λc(2860), Λc(2880), Ξc(3055) and Ξc(3080) as D-wave baryon states in QCD

In this article, we tentatively assign the Λc(2860), Λc(2880), Ξc(3055) and Ξc(3080) to be the D-wave baryon states with the spin-parity JP=32+, 52+, 32+ and 52+, respectively, and study their masses and pole residues with the QCD sum rules in a systematic way by constructing three-types interpolating currents with the quantum numbers (Lρ,Lλ)=(0,2), (2,0) and (1,1), respectively. The present predictions favor assigning the Λc(2860), Λc(2880), Ξc(3055) and Ξc(3080) to be the D-wave baryon states with the quantum numbers (Lρ,Lλ)=(0,2) and JP=32+, 52+, 32+ and 52+, respectively. While the predictions for the masses of the (Lρ,Lλ)=(2,0) and (1,1) D-wave Λc and Ξc states can be confronted to the experimental data in the future.

Deformations of the standard model: SUq(3) flavor symmetry

The quantum group SUq(3) = Uq(su(3)) is taken as a baryon flavor symmetry and exceptionally accurate octet and decuplet baryons mass relations are obtained by accounting for the electromagnetic contribution to baryon masses (to zeroth order). The resulting charge specific q-deformed octet and decuplet baryon mass sum formulas are accurate to 0.02% and 0.08% respectively; a factor of 20 reduction in error compared to the standard Gell-Mann-Okubo mass formulas. An explicit formula for the Cabibbo angle, taken to be , in terms of the deformation parameter q and spin parity JP of the baryons is obtained.

Photoproduction of hidden-charm states in the reaction near threshold**Supported by Major State Basic Research Development Program in China (2014CB845400), National Natural Science Foundation of China (11475227, 11275235, 11035006) and Chinese Academy of Sciences (Knowledge Innovation Project (KJCX2-EW-N01), Youth Innovation Promotion Association CAS (2016367), Open Project Program of State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of

We report on a theoretical study of the hidden charm states in the reaction near threshold within an effective Lagrangian approach. In addition to the contributions from the s-channel nucleon pole, the t-channel D0 exchange, the u-channel exchange and the contact term, we study the contributions from the states with spin-parity JP = 1/2− and 3/2−. The total and differential cross sections of the reaction are predicted. It is found that the contributions of these states give clear peak structures in the total cross sections. Thus, this reaction is another new platform to study the hidden-charm states. It is expected that our model calculation may be tested by future experiments.

Can X(5568) be a tetraquark state?**Supported by National Natural Science Foundation of China (11575110), Natural Science Foundation of Shanghai (15DZ2272100, 15ZR1423100), China Postdoctoral Science Foundation, Open Project Program of State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, China (Y5KF111CJ1), and Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry

Very recently, the D0 collaboration has reported the observation of a narrow structure, X(5568), in the decay process using the 10.4fb−1 data of pp̄ collision at . This structure is of great interest since it is the first hadronic state with four different valence quark flavors, b, s, u, d. In this work, we investigate tetraquarks with four different quark flavors. Based on the diquark-antidiquark scheme, we study the spectroscopy of the tetraquarks with one heavy bottom/charm quark and three light quarks. We find that the lowest-lying S-wave state, a tetraquark with the flavor [su][b̄d̄] and the spin-parity JP = 0+, is about 150 MeV higher than the X(5568). Further detailed experimental and theoretical studies of the spectrum, production and decays of tetraquark states with four different flavors are vital to gain a better understanding of the nature and classification of hadron exotic states.

Analysis of X(5568) as Scalar Tetraquark State in Diquark-Antidiquark Model with QCD Sum Rules**Supported by National Natural Science Foundation under Grant No. 11375063, and Natural Science Foundation of Hebei Province under Grant No. A2014502017

In this article, we take the X(5568) as the diquark-antidiquark type tetraquark state with the spin-parity JP = 0+, construct the scalar-diquark-scalar-antidiquark type current, carry out the operator product expansion up to the vacuum condensates of dimension-10, and study the mass and pole residue in details with the QCD sum rules. We obtain the value MX = (5.57±0.12) GeV, which is consistent with the experimental data. The present prediction favors assigning the X(5568) to be the scalar tetraquark state.

And interactions and the charged charmonium-like state Z(4430)**Supported by Major State Basic Research Development Program in China (2014CB845405), National Natural Science Foundation of China (11275235)

The and interactions are studied in a one-boson-exchange model. Isovector bound state solutions with spin parity JP = 1+ are found from the interaction, which may be related to the observed charged charmonium-like state Z(4430). There is no bound state solution found from the interaction.

The Ξ* and Ωη Interaction Within a Chiral Unitary Approach**Supported by the National Basic Research Program (973 Program Grant No. 2014CB845406), and the National Natural Science Foundation of China under Grant Nos. 11475227, 11265014, and the Open Project Program of State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, China No. Y5KF151CJ1

In this work we study the interaction of the coupled channels Ωη and within the chiral unitary approach. The systems under consideration have total isospins 0, strangeness S = −3, and spin 3/2. We study the s wave interaction which implies that the possible resonances generated in the system can have spin-parity JP = 3/2−. The unitary amplitudes in coupled channels develop poles that can be associated with some known baryonic resonances. We find there is a dynamically generated 3/2− Ω state with mass around 1800 MeV, which is in agreement with the predictions of the five-quark model.

Formula omitted] and [formula omitted] interactions and the LHCb hidden-charmed pentaquarks

Very recently, two hidden-charmed resonances Pc(4380) and Pc(4450) consistent with pentaquark states were observed at the LHCb detector. The two Pc states locate just below the D¯Σc⁎ and D¯⁎Σc thresholds with mass of gaps about 5 and 15 MeV, respectively. Inspired by this fact we perform a dynamical investigation about the D¯Σc⁎(2520) and D¯⁎Σc(2455) interactions which are described by the meson exchanges. A bound state which carries spin-parity JP=3/2− is produced from the D¯Σc⁎(2520) interaction, which is consistent with the Pc(4380) observed at the LHCb detector. From the D⁎Σc(2455) interaction, a bound state with 5/2+ is produced, which can be related to the Pc(4450). The results suggest that the Pc(4380) and Pc(4450) are good candidates of D¯Σc⁎(2520) and D¯⁎Σc(2455) molecular states, respectively.

χc0(1P) decay into [formula omitted] in search of an I = 1, 1/2− baryon state around [formula omitted] threshold

We present the theoretical study of the process χc0(1P)→Σ¯Σπ decay, by taking into account the πΣ and πΣ¯ final state interactions of the final meson-baryon pair based on the chiral unitary approach. We show that the process filters the isospin I=1 in the πΣ channel and offers a reaction to test the existence of an I=1 state with strangeness S=−1 and spin-parity Jp=1/2− around the K¯N threshold predicted by some theories and supported by some experiments.